Lubricating compositions and additives therefor



properties to various lubricants.

United States Patent Office 3,198,737 Patented Aug. 3, 1965 This invention relates to lubricants, particularly those useful for lubrication under severe operating conditions, such as those under extreme high speed and at high temperatures and to a new and novel class of compounds therefor.

It is well known that the high pressure occurring in 'certain types of gears and bearings may cause rupture of lubricant films with consequent damage to the machinery. It is known that various base lubricants can be improved in their protective properties for rubbing surfaces by the addition of certain substances, so-called extreme pressure agents, so that excessive Wear, scufiing and seizure which normally follow a break in the film lubricant are minimized or prevented.

It is known that certain compounds of metal-reactive elements, such as certain compound of chlorine, sulfur and phosphorus, as Well as certain other compounds, such as some compounds of lead, impart extreme pressure Notable among the substances heretofore used are the lead soaps, phosphoric acid esters, free or bound sulfur and certain chlorinated organic compounds. A principal object to many of these extreme pressure agents is their generally high reactivity with the metallic surface, causing etching, corrosion and discoloration of the metal surface. Another objection to chemically reactive extreme pressure agents is that they alter the original chemical nature of the contacting surface, which under certain conditions is undesirable. Additionally, because of the activity of agents of this type, they usually are depleted rapidly resulting in only a temand the thioether thereof by the formula V\ "-X '-o co-n-s-(ou Z IZ CH /HSROOO R j: R A z/n porary solution to the problem of extreme pressure lubrication.

It has now been discovered that improved extreme pressure lubricants are provided by a suitable lubricating oil composition containing a small amount of a particular class of oil-soluble polysulfoxyl esters obtained by hydrogen peroxide or per(carboxylic) acid treating (a) an ester of a long chain unsaturated fatty acid, RCOOH, and a polyoxyalkylene diol or its thio derivative having the formula HO- R X R0 J! /y (I) where R and R" are the same or different alkyl radicals of from 2 to 8, preferably 2 to 3 carbon atoms, X is oxygen or sulfur and x and y are integers of at least 1, preferably 1 to 6 with (b) a mercapto compound such as a mercapto acid, alcohol, ether or ester so that the end product has at least 1 and preferably 2 thioether radicals fiS(CH ),,Z, where Z is OR"' or -COOR"' and the R' is hydrogen or a C alkyl radical and n is an integer of from 1 to 4, preferably 1. The maximum number of units in the compound thus formed depends on the degree of unsaturation of the ether-ester. The unsaturated fatty acid ester of the polyoxyalkylene glycol may be represented by the corresponding formula On treatment of compounds of Formula II with hydrogen peroxide or per(carboxylic) acid the sulfur in said compounds (II) is converted to sulfoxide groups and the final compound thus formed has the formula where the symbols Z, R, R, R", X and n are the same as in (II). The X* is SO when X is S.

The ether-esters are prepared by esterifying a long chain unsaturated fatty acid such as unsaturated fatty acid having at least 18 carbon atoms, e.g. oleic acid, linoleic acid, linolenic acid, erucic acid, ricinoleic acid and the like with a polyoxyalkylene diol or the thio derivatives thereof, such as polyethylene glycols, e.g. diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, dibutylene glycol, 2,2- thiodiethanol, 3,3-thiodipropanol and the like. Esters of these materials include diethylene glycol dioleate, triethylene glycol dioleate, dipropylene glycol dioleate, diethylene glycol linoleate, tetraethylene glycol ricinoleate, dibutylene glycol oleate, 2,2'-thiodiethanol dioleate, 2,2- thioethanol diricinoleate, 2,2-thiodiethanol linoleate and the like.

The ether-ester (1) is then reacted with (2) a mercapto compound such as mercapto aliphatic carboxylic acids, e.g., mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, or mercaptoalkanols such as 2-mercaptoethanol, 2- and 3-mercaptopropanol, 2-, 3- and 4- mercaptobutanol or ethers of said mercapto alcohols such as methyl or octyl Z-mercaptoethanyl or mercapto esters, e.g., ethyl mercaptoacetate or ethyl mercaptobutyrate, and mixtures thereof. The reaction of 1) and (2) can be carried out by the methods described in Koenig et al. JACS 79, 362 (1957) or Fitzgerald, Jr. Org. Chem. 22, 197 (1957), and preferably at low temperatures, from room temperature to about 50 C., in the presence of a free radical catalyst such as azo or peroxide catalysts or ultraviolet light and a non-reactive solvent such as henzene, toluene, xylene, or the like. Suitable initiators include various free radical-yielding, heterocyclic and alicyclic peroxides, such as diethyl peroxide, tertiary butyl hydroperoxide, dibenzoyl peroxide, dietertbutyl peroxide, dimethylthienyl peroxide, dicyclohexyl peroxide, dilauroyl peroxide and urea peroxide. These are mentioned, by

,way of non-limiting examples of Suitable organic peroxides. Other initiating compounds known include emulsion redox systems, such as a mixture of sodium bisulfite and persulfate, ammonium persulfate, alkali metal perborates, azo compounds, such as alpha,alpha-azodiisobutylronitrile, etc.

The following examples illustrate the preparation of suitable intermediate additives for use in preparing the sulfoxide derivatives of the present invention.

INTERMEDIATE COMPOUNDS Example I pressure. The resulting product was a mixture of the 9- and 10-carboxylmethylmercaptostearate diester of diethylene glycol.

Example 11 About 600 grams of triethylene glycol dioleate and 223.5 grams of mercaptoacetic acid were mixed in a flask at 20-25 C. About 240 drops (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture was diluted with 2 volumes of diethyl ether, washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C. and 2 mm. pressure. The resulting product was a mixture of the 9- and 10-carboxymethylmercaptostearate diester of triethylene glycol.

Example III About 600 grams of diethylene glycol ricinoleate and 223.5 grams of mercaptoacetic acid were mixed in a flask at 20-25' C. About 240 drops (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture was diluted with 2 volumes of diethyl ether, washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C., and

2 mm. pressure. The resulting product was a mixture of the 9- and 10-carboxylmethylmercapto-12-hydroxylstearate diester of diethylene glycol.

Example IV About 600 grams of diethylene glycol dioleate and 190 grams of mercaptoethanol were mixed in a flask at 20- 25 C. About 240 drops (30 drops at a time) of t-butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reaction mixture Was diluted with 2 volumes of diethyl ether, washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C. and 2 mm. a pressure. The resulting product was a mixture of diethylene glycol di(9- and 10-[2-hydroxyethylmercapto]-stearate).

Example V About 600 grams of 2,2'-thiodiethanol dioleate and 223.5 grams of mercaptoacetic acid were mixed in a flask at 20-25 C. About 240 drops (30 drops at a time) of t butyl hydroperoxide were added over a period of 2 hours and the temperature was kept at about 37 C. The reac tion mixture was diluted with 2 volumes of diethyl ether, 'washed with 12 liters of water to pH 4, dried over Na SO filtered and the solvent stripped at 155 C. and 2 'mm. pressure. The resulting product was a mixture of 2,2'-thiodiethanol di(9- and 10-carboxymethylmercaptostearate).

The final sulfoxide compounds of this invention are prepared by treating the above-described intermediate compounds represented by Formulas I and II and illustrated by Examples I-V with an inorganic acid and an aqueous solution of hydrogen peroxide or with a per(carboxylic) acid at between and 100 C., preferably at ambient temperature to form compounds represented by Formula 111.

The aqueous solutions of hydrogen peroxide which may be used include those normally available in commercial quantities, for example 100 volume hydrogen peroxide solution which contains about 30% by weight of hydrogen peroxide (H 0 Aqueous solutions of hydrogen peroxide containing concentrations of hydrogen peroxide be- .tween Sand 95% H 0 by weight may be used tocarry out the treatment. Hydrogen peroxide solutions containing between 25 to 85% by weight of H 0 are usually used and preferably solutions containing between 30 and 50% by weight H 0 Inorganic acids have been found suitable for use according to the process of the present invention, such as hydrochloric, sulfuric and phosphoric acid and these acids are conveniently used in the strengths in which they are normally available in commercial quantities. The concentrations of the aqueous solutions of inorganic acid suitable for use vary with the particular acid being used. Acids in relatively high concentrations are usually preferred but it has been found that dilute aqueous solutions containing up to 50% by weight of the acid are also suitable.

Suitable organic peracids which may be used according to the present invention are the peracids of the lower fatty acids, such as performic acid, peracetic acid, perpropionic acid and perbutyric acid, the peracids of the substituted lower fatty acids, such as monochlorperacetic acid and trichlorperacetic acid and the peracids of the aromatic carboxylic acids, such as perbenzoic acid. Of these, performic acid, peracetic acid and trichlorperacetic acid ar the most effective and performic and peracetic acids are preferred.

The peracids may be used in the present process either as such or in statu nascendi. Thus, instead of treating the compound of Formula II with a performed organic peracid, they may be treated with a mixture of the organic acid and hydrogen peroxide, these reagents may be used in stoichiometri'c proportions but generally it is preferable to employ excess of the acid.

The peroxide of peracid treatment of thioether-ester compounds is generally effected at ambient temperatures,

although any other convenient temperature, such as between 0 and C., may be employed. The thioetherester compound and the peracid should be well agitated to ensure intimate contact and, with good agitation, the reaction should be completed in a period of from 30 to minutes.

A convenient method of effecting the treatment is to mix a thioether-ester compound with the necessary proportion of aqueous solution of hydrogen peroxide and with the organic acid. The hydrogen peroxide solution is conveniently used in the form in which it is readily available commercially, for example as 100-volume" hydrogen peroxide which contains 30% by Weight of hydrogen peroxide. Similarly, the organic acid is conveniently used in the form in which it is available commercially. Thus, formic acid may be used as the commercial acid containing 90% by volume of H-COOH, Whereas acetic acid can be used as glacial acetic acid. More dilute aqueous solutions of formic acid may be used, such as those containing 20 to 50% by volume of H-COOH. In

the case of solid organic acids such as trichloroacetic acid, these may be dissolved in a suitable solvent such as water or a low boiling alcohol before adding to the thioetherester compound and hydrogen peroxide solution, or they may be dissolved or dispersed in the hydrogen peroxide solution before mixing and reacting the constituents.

The following examples illustrate the preparation of the final additives (sulfoxides) of this invention.

FINAL PRODUCT Example IA About one mol of the additive of Example I (mixture of 9- and l0-carboxymethylmercaptostearate diester of diethylene glycol) Was mixed with an equivalent amount of hydrogen peroxide-acetic acid solution and the mixture was stirred for 24 hours at room temperature. The sulfoxide product recovered by ether extraction was a mixture of 9- and 10-carboxymethylsulfoxy stearate diesters of diethylene glycol. The product is oil-soluble and exhibits excellent extreme pressure properties.

Exampe HA The procedure of Example IA was followed using the additive of Example II to form as the final product the mixture of 9- and 10-carboxymethylsulfoxystearate diesters of triethanol glycol.

Example IIIA The mixture 9- and 10-carboxymethylmercapto-12-hydroxystearate diester of diethylene glycol was treated with peracetic acid solution for 24 hours at room temperature and recovered by ether extraction was 9- and 10-carboxymethylsulfoxy-l2-hydroxystearate diester of diethylene glycol.

Example IVA The procedure of Example IA was followed to treat a mixture of 2,2-thiodiethanol di(9- and IO-carboxymethylmercaptostearate) to form a mixture of 2,2'-sulfoxydiethanol di(9- and 10 carboxymethylsulfoxystearate) which product exhibited excellent extreme pressure properties.

Example VA 2,2-tnodiethanol di(9- and lO-carboxymethylmercaptostearate) was treated with a solution of hydrogenperoxide and acetic acid at room temperature for 24 hours and on ether extracting 2,2-sulfoxydiethanol di(9- and 10carboxymethylsulfoxystearate) was recovered.

Other compounds illustrating the invention iriclude dicarboxymethylsulfoxystearate diester of diethylene glycol and di(carboxymethylsulfoxy) substituted 2,2-sulfoxy diethanol dioleate.

The sulfoxy-modified polyether-esters are oil-soluble and can be used in amounts or" from about 0.5% to about 20%, preferably from about 1% to about 5% by weight.

Lubricating oils useful for the preparation of compositions of this invention can be one or more of a variety of synthetic oils or natural hydrocarbon oils having a viscosity range of from 50 SUS at 100 F. to 250 SUS at 210 F. (SAE viscosity number ranging from SAE 10W to SAE 90). tained from parafiinic naphthenic, asphaltic or mixed base crudes, and/or mixtures thereof refined as by extraction acid treatment clay treatment. Synthetic oils include polymerized olefins, alkylated aromatics, isomerized waxes, copolymers of alkylene glycols and alkylene oxide (Ucon fluids) which are described in U.S. Patents 2,425,755, 2,425,845 and 2,774,73 such as Ucon 50HB 170, Ucon 50118660 or Ucon LBSSOX and which are copolymers of ethylene and 1,2-propylene oxides, the monoand diols, as well as their ether derivatives; organic esters of aliphatic dibasic acids such as di-2-ethylhexyl sebacate or di-2-ethylhexyl adipate and the like. The hydroearbon oils may be blended with fixed oils such as castor oil, lard oil and the like and/or synthetic oils as mentioned or silicone polymers and the like. Typical oils of this type include petroleum motor oils which are (A) paraffinic in character and (B) naphthenic in character having the following properties:

(SAE 10W) (SAE 30) Pour point, F l 5 Flash, F 300 415 Visocisity, SUS at 210 44 58 Viscosity index 90 60 Other suitable oils are the gas turbine lube the following properties:

Grade 1010 1065 Flash, 000, F 300 465 Pour, F 0 Visocity, SUS at 100 F 59. 4 530 Neutral number 0. 02 0. 01 Ash None None The natural hydrocarbon oils can be ob- 1 iCOMPOSI T-ION B Example IIA additive 2%. 1010 mineral oil Essentially balance.

- COMPOSITION C Example IIIA additive 2%. 1010 mineral oil Essentially balance.

COMPOSITION D Example 1V additive 2%. 1010 mineral oil Essentially balance.

COMPOSITION E Example IIA additive 1%. SAE 30 mineral oil Essentially balance.

COMPOSITION F Example VA additive 2%. SAE mineral oil Essentially balance.

COMPOSITION G Example IA 2%. Laurie acid 2%. SAE 90 mineral oil Essentially balance.

COMPOSITION H Example IA additive 5%. Ucon 50HB660 (polyethylene-propylene glycol having a SUS at F. of 660) Essentially balance.

. COMPOSITION aI Example IA additive 2%. Di-2-ethylhexyl sebacate Essentially balance.

Speed r.p.m 3,200 Oil temperature C 100 Oil flow-rate cc./sec 10 Load in increments; 5 min. at each setting.

Results of the evaluations are given in Table I and for purpose of comparison, the results obtained from the use of the base oil alone and With other known extreme pressure compositions are also given.

TABLE I Composition: Score load, lbs/in.

A, B, C andE 12,000.

1010 mineral oil+2% C alkenyl succinic acid 1010 mineral oil+2% malonic acid 2,800. 1010 mineral oil+2% 3-hexadecyl adipic acid 1,400. 1010 mineral oil+2% dodecylmercaptosuccinic acid 1,400. 1010 mineral oil+10% glycerol monooleate 1,800. 1010 mineral oil 2% ess) 600. 1010 mineral oil 600.

The data show the outstanding enhancement of the loadcar-rying ability of the oil effected by the mercapto-containing compounds of the invention, as represented by those of Compositions A, B, C and E. On the other hand, malonic acid, succinic-acid, 3-hexadecyl adipic acid and C -alkenyl succinic acid as well as sulfur-containing acids outside the scope used by applicant such as dodecyl-mercaptosuccinic acid are poor load carrying agents.

1,400 (3,200 r.p.m.).

The sulfoxide-containing compounds of this invention are useful also for providing superidr-load-carrying properties for lubricating oils which contain minor amounts of other agents, such as silicone anti-foaming agents, a1l yl phenol anti-oxidants, polyacrylate ester viscosity-index improvers, long chain acids such as lauric and oleic acids as oiliness agents and the like.

I claim as my invention:

1. A lubricating oil comprising a major amount of lubricating oil and from about 0.5% to about by weight of a disulfoxy derivative having the formula O CH Z S I where Z is an oxygen-containing radical selected from the group consisting of OR' and COOR'", where R' is selected from the group consisting of hydrogen and a C alkyl radical and n is an integer of from 1-4 of an ester of an unsaturated fatty acid having 18 carbon atoms and a polyoxyalkylene diol.

2. The composition of claim 1 wherein the oil is a mineral lubricating oil and the sulfoxy portion of the ester is so CH 2 T where Z is a COOH radical and n is an integer of from 1 to 4.

3. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 20% by weight of an oil-soluble di(carboxy C alkyl sulfoxy) substituted stearate diester of polyethylene glycol.

4. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5 to about 20% by weight of an oil-soluble di(carboxy C alkyl sulfoxy) hydroxystearate diester of polyethylene glycol.

5. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 20% by Weight of an oil-soluble di(carboxy C alkyl sulfoxy) 2,2'-sulfoxydiethanol dioleate substituted ester of oleic acid and polyoxyethylene glycol.

6. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 1% to about 5% by weight of dicarboxymethylsulfoxystearate diester of diethylene glycol.

7. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 1% to about 5% by weight of di(carboxymethylsulfoxy) substituted 2,2'-sulfoxydiethanol dioleate.

8. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 1% to about 5% by weight of a mixture of 9- and 10- carboxymethylsulfoxystearate diester of diethylene glycol.

9. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 1% to about 5% by weight 2,2-sulfoxydiethanol di(9- and lO-carboxymethylsulfoxystearate) References Cited by the Examiner UNITED STATES PATENTS 2,192,721 3/ 40 Toone 260400 2,503,401 4/50 Mattano et al 25248.6 2,540,570 2/51 Cyphers 252-486 2,577,719 12/51 Stewart 25248.6 2,623,887 12/52 Matuszak 260400 2,892,853 6/59 Koenig et al 25248.6 X 2,994,662 8/61 Calhoun et al. 2'52--48.6 3,041,284 6/62 Calhoun et al. 252-486 DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner. 

1. A LUBRICATING OIL COMPRISING A MAJOR AMOUNT OF LUBRICATING OIL AND FROM ABOUT 0.5% TO ABOUT 20% BY WEIGHT OF A DISULFOXY DERIVATIVE HAVING THE FORMULA 